Capabilities of a .45-70 Rebarreled Mosin (or Siamese Mauser)


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luisespinal
June 5, 2013, 04:36 PM
=== edit ===
By mistake I repeatedly wrote ".40-70" when I meant to say ".45-70". I corrected my post to reflect that.
==========

Hello,

Mods, please let me know if I created this thread in the right forum.

I was wondering if there was a a strong and modern .45-70 rifle, not single shot, capable of handling the full extend of the cartridge with modern loads. I was thinking maybe the Henry .45-70.

But then, I learned of options to re-barrel Mosins to that caliber (by replacing the original barrel with a brand new one just for that caliber). And I also saw a Siamese Mauser modded for that cartridge on gunbroker (don't know if that had a new barrel or a rebarreling of the original). :what:

And that got me thinking, ignoring the cost for a moment, if such a modified mosin would fit the bill.

I really do not know much about the Siamese Mauser option when it comes to pressure capabilities.

For the Mosin, some places state it is capable of handling 46.6K to 47K psi. Others say 56k psi. And wikipedia states the 7.62x52mmR tolerates a maximum pressure of 52K psi. So far, it has been unclear to me how hard one can push a load on the mosin.

OTH, when consulting the Hodgdon cartridge loads (http://data.hodgdon.com/cartridge_load.asp), the recommended max loads for the ruskie round are just below the max loads for the .40-70 on what the chart calls a "modern" rifle (not lever or trapdoor, as per the chart.) Those max loads are around 47K PSI for loading .40-70 and around 46K PSI for loading the good old ruskie.

The chart would seem to suggest that a mosin in its original configuration is strong enough to handle pressures just a bit below the max pressures on a modern .45-70 load. That would be just fine with me.


Gun collective, what say you?

I really like my current 90/31, and I'm in the process of finding and acquiring more collectible-grade milsurps, mosins in particular.

As a result, I'm leaning 2/3's in favor of finding an already beat up Mosin or a Bubba, and have it modded for the .45-70 just for poops and giggles, even if it is not necessarily the most cost efficient thing to do.

But I would like to know your opinion, if you have done/owned one such beast or known of one before hand. Mostly pros and cons in terms of capabilities, or if it would be better to use a different milsurp platform.

Chances are I can still get a receiver and a bolt for less than the price of a mosin in good condition (I've seen a few like that online and on local gunshops.) Either that or getting a Mosin with the barrel already shot to hell. :evil:

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Reloadron
June 5, 2013, 06:00 PM
While there were several versions of the 40-70 rifle cartridge it has not been around for years. Your link Hodgdon cartridge loads will get you to the 45-70 cartridge which remains popular today in a variety of rifles including lever guns. Would the 45-70 be what you have in mind?

Ron

Jim Watson
June 5, 2013, 06:14 PM
.40-70?
You repeatedly post ".40-70" yet most of your references seem to be to the much more common .45-70.

Let's assume you are talking about a .45-70.
Most searches on Mosin Nagant .45-70 come up with Jim Green.
His shop website with a video on the conversion is at:
http://www.downeastgunworks.com/?page_id=397

The load he uses is in the 38000-40000 CUP range as listed for Marlin 1895.
If you want more kick, you should discuss with him or other gunsmith about loading up to the chamber pressure of the original 7.62. I don't see why you couldn't but I am not going to say you can.

The Siamese Mauser is a better known conversion on a better action, but they are a lot harder to find now than a MN.


If you really want a .40 caliber, discuss the possibility of a bolt action .405 Winchester, for which ammunition is reasonably available again.

luisespinal
June 5, 2013, 07:12 PM
Reloadron/Jim, yep that was a typo. Thanks for catching it up. I mean to say ".45-70". I've fixed my original post to reflect that. Thanks!

luisespinal
June 5, 2013, 07:24 PM
Jim, yes, Mr. Green's gunsmith shop is the one I was considering. I'm already contacting him in that regard. Since I just purchased some new toys and ammo (and I'm about to set myself up for reloading), I'll have to wait for a few months before I go ahead with the order (otherwise my wife will kill me.)

I think I will be pleasantly surprised with the final work. But was wondering if other people have done similar work on milsurps (in particular mosins, but all milsurps in general), and what their experiences (good or bad) have been.

There was a siamese mauser rebarreled for this cartridge which sold for a decent price. For the reasons just mentioned, I simply could not buy it when I saw it. There is another one on gunbroker, but it is over a grant.

I'm sure it's a nice and fine piece, but I'd rather save for a brand new Ruger of that caliber (or something else) if I were to spend that much on it.

Reloadron
June 5, 2013, 08:04 PM
I'll have to wait for a few months before I go ahead with the order (otherwise my wife will kill me.)

It's wise to start doing a little homework and thinking well in advance, additionally nobody here would want your wife to kill you, let alone over a new rifle purchase. Though once I did get a gun for a former wife and it was a great trade. :)

I would start by looking at cost. There is no way I would lay down a grand for any Mauser converted to the 45-70 Government cartridge. Not when I can buy a Marlin Guide Gun designed to handle the modern loadings of the 45-70 cartridge. There is no shortage of fine new rifles in the 45-70 chambering.

Rechambering the older strong Mauser actions in a variety of sporting calibers has been going on forever. The trick is to make sure the action can handle the new chambering. About 15 years ago I took several NRA gunsmithing classes in NC, just summer side learning. A fellow by the name of James Messer was a great instructor and mentor.

The video suggested by Jim is a very good video as it shows the steps involved in doing a caliber conversion beyond the barrel work like opening a bolt face and opening a magazine well.

Since whatever it is it will be your rifle you need to weigh out the good and bad of each possibility.

Ron

tyeo098
June 5, 2013, 08:18 PM
Ask the guys over at WeaponsGuild.

Some of them are known to be crazy enough to have done this. (Or worse... theres a 50BMG AK going on over there...)

Jim Watson
June 5, 2013, 08:46 PM
I don't see a price for the Green conversion, but it won't be cheap.
This is the sort of stuff I look for from a good DIY.

luis.espinal
June 5, 2013, 09:31 PM
Ask the guys over at WeaponsGuild.

Hmmm, didn't about that site. I'll check it out. Thanks.

Some of them are known to be crazy enough to have done this. (Or worse... theres a 50BMG AK going on over there...)

Holy smokes.

luis.espinal
June 5, 2013, 09:43 PM
I don't see a price for the Green conversion, but it won't be cheap.

I got a quote from him. Since it was sent privately, I'm a bit hesitant to mention it (I'll ask if it's ok to share, and if so, I'll post it.)

It is certainly not cheap, specially if compared to the price of an ok-quality mosin. But it is on par with a decent rifle. It will take a few months to save for it (wife is the CFO of the house, so I work on a limited budget :))

This is the sort of stuff I look for from a good DIY.

Indeed. I'm a DIY guy myself (mostly electronics and carpentry), and gunsmithing (at least the basics) is something I want to learn. We currently live in a condo, so my space is limited to what I can do. We might buy a home or relocate to another city soon. Then I'll be able to seriously invest the time and money into this.

Conceptually, this type of job looks simple (obviously with a million critical details.)

To create the barrel, a barrel blank, a lathe, bores and threading kits I guess. CNC machinery as well (???)

Modifying bolt and receiver however, I cannot even scratch an idea of what it entails, let alone doing it safely. Much to learn, much to learn.

luis.espinal
June 5, 2013, 09:55 PM
FYI, I did registered to WeaponsBuild.

Holy smokes, they really do build insane stuff. I saw posts of a Mosin reworked for the 450 Marlin cartridge. I'm going with this idea. It will take a couple of months, but once I have my new toy, I'll post back with the results.

Thanks.

Reloadron
June 6, 2013, 05:05 AM
To create the barrel, a barrel blank, a lathe, bores and threading kits I guess. CNC machinery as well (???)


A CNC machine while nice is not at all needed. A good lathe and milling machine are pretty much a must. Starting with a barrel blank that is rifled takes considerable time, effort and skill to fit to an action.

Yes, cost for this type of work is high but for good reason. The needed equipment is expensive.

Since you mention:
I'm a DIY guy myself (mostly electronics and carpentry)

A good lathe or milling machine will have a 5 HP motor or larger. Good equipment will require 3 phase power. Now if you don't have 3 phase things get expensive getting it.

All in all a good smith has expensive tools and very expensive small machine shop. These cost are passed along in the work rates including labor time. Caliber conversions can become far from an inexpensive proposition. :)

Ron

Clark
June 6, 2013, 10:48 AM
http://www.thehighroad.org/showthread.php?t=9987&highlight=relief

I rebarreled a Mosin Nagant to 45/70 in 2003 per the above thread.

The bolt face needs to be relieved to fit the larger case head and rim thickness. Notice the difference between the stock bolt face and the 45/70 bolt face.

The breech of the barrel needs to be relieved for the extractor.
The bolt only rotates 90 degrees, but when the extractor width is added, that makes nearly 180 degrees of extractor relief cut. You don't want a full 180 degrees, because you want more than 180 degrees of breech face that stands up to the rim when the firing pin pushes it forward.

As far as how much pressure a bolt action can take, I have overloaded a number of them to find out. When you compare the bolt lugs and abutments on an MN to a Win M70, Rem700, or Sav110, you can see they are all in the same ball park.

In all my years of overloading guns to see what they can take, I have found the most important thing to be "How thick is the steel?".

luisespinal
June 6, 2013, 10:57 AM
It's wise to start doing a little homework and thinking well in advance, additionally nobody here would want your wife to kill you, let alone over a new rifle purchase. Though once I did get a gun for a former wife and it was a great trade.

I would start by looking at cost. There is no way I would lay down a grand for any Mauser converted to the 45-70 Government cartridge. Not when I can buy a Marlin Guide Gun designed to handle the modern loadings of the 45-70 cartridge. There is no shortage of fine new rifles in the 45-70 chambering.

Indeed. Fortunately it won't be a grant, but it won't be cheap :) Just out of curiosity, how does the Henry or the H&R Handi rifles fair up when handling modern loads on the 45-70?

Rechambering the older strong Mauser actions in a variety of sporting calibers has been going on forever. The trick is to make sure the action can handle the new chambering. About 15 years ago I took several NRA gunsmithing classes in NC, just summer side learning. A fellow by the name of James Messer was a great instructor and mentor.

Cool. Not to derail the original topic of this thread, I've been considering some of the online gunsmith schools out there (http://www.americangunsmith.com/, http://www.moderngunrepair.com/), plus some machining courses at the local community college.

So far, those are the only options I'm aware of where I live (South Florida.) Any recommendations on how to acquire the basics of the trade/skill?

Reloadron
June 6, 2013, 06:13 PM
Indeed. Fortunately it won't be a grant, but it won't be cheap :) Just out of curiosity, how does the Henry or the H&R Handi rifles fair up when handling modern loads on the 45-70?



Cool. Not to derail the original topic of this thread, I've been considering some of the online gunsmith schools out there (http://www.americangunsmith.com/, http://www.moderngunrepair.com/), plus some machining courses at the local community college.

So far, those are the only options I'm aware of where I live (South Florida.) Any recommendations on how to acquire the basics of the trade/skill?

As far as I know all of the new modern rifles like the Henry, H&R, Marlin, Winchester and other rifles chambered for the 45-70 Government will handle the newer modern loads. The only rifle I downloaded for was my 1873 SA Trapdoor where I duplicated as best the original black powder loadings. I don't know of any modern day manufactured rifles chambered in 45-70 that won't handle the modern loads. Not to say there are none, just to say I am not aware of any. If and when you decide just shop wisely and continue to do your homework.

As to online gunsmith courses I am of no help. The courses I took years ago were NRA courses through Montgomery Community College in Troy NC. It was something my brother-in-law and I did for the heck of it each year. It was fun and relaxing and just something we enjoyed. I will say this. Take any basic machinist courses you can at a community college. Developing machine shop skills is of paramount importance. Courses like these locally are normally inexpensive and a great help. Till I recently retired I had full access to the small prototyping machine shop where I worked. Having that access was priceless, especially for an electrical engineering type. :)

Ron

luis.espinal
June 7, 2013, 06:59 PM
http://www.thehighroad.org/showthrea...ghlight=relief

I rebarreled a Mosin Nagant to 45/70 in 2003 per the above thread.

Uh, I wonder I missed your thread when I did the search. Thanks!

luis.espinal
June 7, 2013, 07:11 PM
As far as I know all of the new modern rifles like the Henry, H&R, Marlin, Winchester and other rifles chambered for the 45-70 Government will handle the newer modern loads. The only rifle I downloaded for was my 1873 SA Trapdoor where I duplicated as best the original black powder loadings. I don't know of any modern day manufactured rifles chambered in 45-70 that won't handle the modern loads. Not to say there are none, just to say I am not aware of any. If and when you decide just shop wisely and continue to do your homework.

I guess one thing that got me confuse (or is still getting me confused) is what I see in some reloading data charts. For example, in the hodgdon reloading page (http://data.hodgdon.com/cartridge_load.asp) (see link) makes distinction between lever action rifles and what it calls "modern rifles" as follows:

Modern Rifle (Ruger No.1 and No.3 single shots, Browning 1885 single shots and Siamese bolt action rifles. Max pressure, 50,000 CUP. Do not use these data in either of the prior two sections of 45-70 data (Trapdoor and Lever Actions)

Lever Actions (These data are intended for the 1895 lever action Marlin ONLY. Max pressure, 40,000 CUP. Do not use these data in any of the firearms listed in the Trapdoor section. Do not use pointed bullets in any rifle with a tubular magazine.)

Even though it solely mentions the Marling as a lever action (and makes no mention of other single shot rifles in the "modern rifle" data), it got me wonder about the Henry or the H&R Handi.

I might still go for the modded mosin option (I like the idea of a 3-round bolt action), but the main premise that got me to consider this project (that the only way to use a modern load was with one of those $1K Ruger single shots) is not true at all.

Reloadron
June 7, 2013, 09:34 PM
Many loading manuals differentiate the 45-70 loads. Something to keep in mind is not all modern rifles will handle the hotter loadings. Just as an example Sierra actually gives 3 loadings for a 300 grain hollow point bullet.

1, Loads for the 1873 Springfield Trapdoor, Remington Rolling Block and other old black powder rifles but also go on to say replicas and other modern reproductions. So the rifle end user needs to know what he or she has. A powder example would be IMR 4227 with velocities between 1450 to 1650 FPS (Springfield Trapdoor) 26.8 to 32.0 Grains of powder. Never exceeding 32.0 Grains.

2. Loads for the Model 1886 Winchester, Sharps-Borchardt, Remington and Navy Arms Rolling Block Designs. Again using IMR 4227 with velocities between 1600 and 1850 FPS (Winchester 1886) 31.8 to 37.0 Grains of powder. Never exceeding 37.0 Grains.

3. Loads for the Model 1895 Marlin, Ruger No. 1 and Ruger No. 3, and Siamese Mauser Bolt Action. Again using IMR 4227 with velocities between 1950 and 2150 FPS (Marlin Model 1895) 39.2 to 44.8 Grains of powder. Never exceeding 44.8 Grains.

Loading manuals will vary slightly in how they present things. As can be seen Sierra breaks things down into 3 ranges of loads depending on the rifle. The trick again is knowing what you have and what it can safely handle. Like Clint Eastwood said, "A man has got to know his limitations". Different manuals will also mention different makes and models of rifles. This is why most hand loaders have and use several manuals and compare their notes.

The above loading data is for reference only and for example purposes only!

When I load for anything I start low and work up looking for pressure signs. I increase my charge looking at the rifle's accuracy. Faster is not always more accurate.

Ron

StrawHat
June 8, 2013, 06:21 AM
...I saw posts of a Mosin reworked for the 450 Marlin cartridge. I'm going with this idea. It will take a couple of months, but once I have my new toy, I'll post back with the results.

Thanks....
I know nothing about the Moisin Nagant, but nearly any modern bolt action rifle is available with a bolt head to handle the 450 MArlin. Perhaps that would be an easier build for you.

luis.espinal
June 8, 2013, 09:16 AM
Thank you all for sharing your thoughts and experiences. I think I have a clearer picture now of what can be done with this cartridge. Perhaps not a complete picture, but certainly far clearer than when I started. I will take more time to really research what I can buy, what I truly, and which of the options available will suit me best.

Thank you all.

Gunnerboy
June 9, 2013, 11:39 AM
Mosins are a very tough action, had a customer at the shop i work at complain his mosin kept splitting cases, and i asked to see the ammo and guess what haha he was shooting 7.62x51 Nato out of a 7.62x54r mosin.... shot a whole box thru that rifle and didnt ruin a thing we checked headspace looked for signs of pressure etc.

luis.espinal
June 9, 2013, 08:26 PM
Damn.

backbencher
June 10, 2013, 09:00 AM
Wonder what sort of group he was getting using .308" bullets in a .311" bore? Gave my brother my "new" jap rifle once to testfire, & some Norma 6.5"mm I had. Turns out it was a 7.7mm, keyholed, split the case.

Best method of test firing I've ever come up w/ - give it to your brother...

Tolkachi Robotnik
June 10, 2013, 10:25 PM
The brass had to be ruined. I wonder how the fired cases extracted, since the .308 has no rim. The two cases have similar loads, but the 7.62X54R has a higher volume. The bases of the cases had to split or at least stretch a great deal. The throat dimensions would help against calamity.

I loaded a few .308 bullets when I started on my M44 loading attempts. They did not shoot all that bad, as the lands are high in the rifling. The burning powder out runs the bullets down the bore via the grooves though, making quite a bit of fire apparent especially if it is toward evening, and it cannot help accuracy to have turbulence like that at the muzzle.

The only Mosins I've heard failed are Bannerman's 30-06 reworks, where they reamed out the chamber deeper, and left the base of the chamber over large, as the 30-06 is a smaller diameter by quite a bit. These split cases, and the barrels had less metal for holding pressure. These 30-06 Mosins were unsafe. Otherwise the Mosin rifles are pretty thick and stable.

Clark
June 12, 2013, 02:25 PM
Who ever's idea it was to production line put a 30-06 reamer in a 7.62x54 chamber, wears the dunce cap of gunsmithing legacy.
Too much gapposis between case and chamber wall.

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